Must-read, front-page NYT article:

In all, nine states have passed measures making it harder to vote since the beginning of 2013. Most have to do with voter ID laws. Other states are considering mandating proof of citizenship, like a birth certificate or a passport, after a federal court judge recently upheld such laws passed in Arizona and Kansas. Because many poor people do not have either and because documents can take time and money to obtain, Democrats say the ruling makes it far more difficult for people to register.

Voting experts say the impact of the measures on voter turnout remains unclear. Many of the measures have yet to take effect, and a few will not start until 2016. But at a time when Democrats are on the defensive over the Affordable Care Act and are being significantly outspent by conservative donors like the Koch brothers, the changes pose another potential hurdle for Democratic candidates this year.